Refresh is changing page

I haven't been able to track down exactly what's causing this, but I'll describe it anyway. I've noticed when refreshing a tab (Cmd+R) or reloading the same URL (Cmd+L, enter) that occasionally it will go to a new, different page I have recently visited in another tab or window. I'm pretty sure it's started happening in the last couple of weeks. Has anyone else seen this?

@leocg Yes it definitely is, and I am on the most current stable version. It just updated a few hours ago, so I hoped it cleared up this bug, but it hasn't. There's also a problem with leaving comments on various websites, where logging into Facebook is needed to comment. Every time I hit the the log in button, the FB login pop up window opens, does a quick something, closes, and the page does nothing but refresh, while erasing everything I'd written...

@sgunhouse It won't allow the log in window to log me in!! Of course I've tried logging in first, but when it's not the site I'm logging into, but just the Facebook commenting feature, you can't log in, until you've written something in the box. I've tried unblocking pop-up boxes, but when I do that, and try to log in, it will go into rapid and endless page refreshing, until I close the window or re-select pop-up blocking! This is definitely an Opera bug, as it occurs on several different websites. As does the arbitrary opening tabs in new windows, for it does it whenever it feels like it, not always or never.